Cutting inserts

Abstract

Improved point geometry is provided for cutting inserts wherein the insert point is subjected to physical and thermal shock in first contacting the stock to be cut and is particularly applicable to cemented carbide or hard metal inserts. It has been found that the provision of about a 104° included angle at the initial work-contacting or lead portion of the insert tip provides improved resistance to physical and thermal shock and longer insert life. While the new cutting insert is especially useful in interrupted cutting where the insert is continuously engaged and disengaged as in the case of a series of cutting inserts in a milling head in contacting an uneven surface, it is also applicable to boring and turning operations and to continuous cutting where the insert point is stressed.

What I claim as new and desire to secure by Letters Patent of the United 
     
       1. A cutting insert having top and bottom polygonal faces, the corresponding edges of said faces being joined by flanks, each flank defining at least one cutting edge with at least one adjoining face, each mutually abutting pair of faces and pair of flanks forming at least one cutting edge point, the leading edge of each cutting edge point being beveled, the angle between the plane of the bevel through the cutting edge point to the flank adjoining the bevel being from about 102° to 
     
     
       2. A cutting insert as in claim 1 in which the flanks are tapered from 
     
     
       3. A cutting insert as in claim 1 in which said flanks are perpendicular to 
     
     
       4. A cutting insert as in claim 1 wherein the angle between the line joining the bevel and the adjoining face, extended along the inserted edge, and the insert edge is about 17°, said line meeting said 
     
     
       5. An insert as in claim 1 in which each cutting edge point is radiused or 
     
     
       6. A cutting insert as in claim 1 in which each cutting edge point is 
     
     
       7. A cutting insert as in claim 4 where each cutting edge is honed to a radius of about 0.004 inch to 0.009 inch.